The embodiment relates to a method for time synchronization and, more particularly, to a method for time synchronization between devices.
For transmission and receipt of data between devices, an attempt to synchronize the devices is made. At this point, based on time information transmitted from a master device or a specific device out of the devices, a device associated with the master device or the specific device generally follows the master device or the specific device in time.
That is, among devices connected over a communication network, a master device transmits a message including a time stamp. The time stamp may include a point in time when the message is transmitted or time information of the master device. Slave devices connected to the master device may synchronize with the master device based on the time stamp included in the message received from the master device.
FIG. 1 is a block diagram illustrating an existing operation for time synchronization between devices.
Referring to FIG. 1, a communication system including an existing server 10 and a client 20 may perform time synchronization in a software handshaking scheme. In the software handshaking scheme, if the client 20 transmits a time request packet to the server 10 (S11), the server 10 may transmit current time information T of the server 10 as a response packet to the client 20 in response to the time request packet (S12).
Using the following Equation 1, the client 20 may set a current time based on the current time information received from the server 10.Current Time of Client=T+RTT/2  [Equation 1]
That is, in a case where the client 20 transmits a time request packet to the server 10 and receives a response signal including current time information T of the server 10, the client 20 may set a current time by subtracting packet transmission time from the entire time elapsed until receipt of the response signal after transmission of the time request packet and then adding a result of the subtraction RTT/2 to the current information T.
The above-described time synchronization between devices in the software handshaking scheme requires transmission, receipt, and interpretation of communications packets between the devices, so that a few ms time error may occur according to data transceiver, receiver, and system. Although accuracy of time synchronization is able to be achieved using this scheme, additional load may occur in the devices since the communications packets need to be interpreted first. Therefore, there may be a limitation to system management and accordingly lead to a waste of time.